World Solving Championship solutions (2)

9/25/2017 – In his report on the Problem Solving event in Dresden, Germany, John Nunn gave you eight problems to solve. A few days ago he showed you of the first four. Today the last four are explained, in John's inimitable style. Play through the solutions and read his comments — this will give you a unique insight into the entertaining and challenging field of chess problems. | Photo: Franziska Iseli

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Solutions, Dresden, 2017 — Part 2

By John Nunn

The 41st World Chess Solving Championship took place during the second week in August in Dresden, the capital of the German state of Saxony. The solving event has been running since 1977 and is a well-established part of the annual World Congress of Chess Competition. Recently it has been utterly dominated by Poland, who have won every year since 2009. We reported on this year’s event two weeks ago. Today we bring you the solutions to the last four problems given there.

The second day of the Championship began with the helpmate round. In a helpmate, both sides are cooperating to help White mate Black (although the moves still have to be legal). Black moves first, with White mating Black on his third move, so the sequence of moves goes B W B W B W mates. There are two parts to this problem, as given below.

[Event "Original for WCSC"] [Site "?"] [Date "2017.08.22"] [Round "?"] [White "Jones, C."] [Black "Helpmate in three (a)"] [Result "*"] [Annotator "Nunn,John"] [SetUp "1"] [FEN "8/8/4b3/ppqk4/1bn1r3/1r2Pp2/1pPP2n1/3R2K1 b - - 0 1"] [PlyCount "6"] [EventDate "2017.??.??"] {Helpmate in 3 a) Diagram b) Move the BQ from c5 to c6 This helpmate might prove more of a challenge, since it defeated some expert solvers. As always with helpmates, spotting the mating position is the key to success. Unfortunately, that's none too easy here, since the congested mass of black pieces can take away squares from the black king, so there are several potential mating squares. However, the black pieces have been cunningly placed to prevent almost all these possibilities working. For example, one idea is for Black to move the c4-knight and play ...Kc4 and ...Bd5; then White could mate by d3 if only he could cover c3 in two moves. However, this isn't possible because the pawn on b2 has been put there to prevent Rb1 and Rxb3. Other attempts fail because there's simply not enough time to set up the necessary position. One example is the attempt to mate Black on c4 after ... Ncxe3, ...Rd4 and ...Kc4, with White playing Re1, Rxe3 and cxb3, which doesn't work because Black lacks a tempo to play ...Bd5. It soon becomes clear that attempts to use the rook from the side are doomed to failure and so the rook has to operate along the d-file; for this the d-pawn has to vanish and the simplest way to achieve this is for Black to take it. This leads to the idea of getting rid of the e3-pawn to allow ...Kd4 and then playing d3 to allow ... Rxd3, with the recapture being mate. For this to work, the e3-pawn must vanish and e5 must be covered, and luckily both these aims can be achieved by playing exf4. The rook on e4 is needed to block e4 at the end, so it must be the knight which plays to f4. Thus Black's three moves would appear to be ...Nf4, . ..Kd4 and ...Rxd3, with White's being exf4, d3 and Rxd3#. Now the composer's true cunning is revealed: this doesn't work because the e3-pawn is pinned and so exf4 is impossible until after ...Kd4, but exf4 is precisely the move that needs to be played to allow ...Kd4. We appear to be in a Catch-22 situation, but the idea looks so promising that it is surely worth pursuing to see if a modification might make it work. How might the e3-pawn be unpinned without wasting a move? The key idea, which is a little tricky to see, is to play d4 rather than d3. All the other moves remain the same, except that ...Kd4 is now a capture while ...Rxd3 isn't. This also serves to uniquely determine the move-order because the only one of Black's three moves that he can reasonably play in the diagram is ... Nf4, giving the solution} 1... Nf4 2. d4 Rd3 3. exf4 Kxd4 4. Rxd3# *

The second part is the same problem with the black queen on c6 and not c5:

[Event "Original for WCSC"] [Site "?"] [Date "2017.08.22"] [Round "?"] [White "Jones, C."] [Black "Helpmate in three (b)"] [Result "*"] [Annotator "Nunn,John"] [SetUp "1"] [FEN "8/8/2q1b3/pp1k4/1bn1r3/1r2Pp2/1pPP2n1/3R2K1 b - - 0 1"] [PlyCount "6"] [EventDate "2017.??.??"] {Now we move the queen to c6, which at least means that the e3-pawn will not be pinned, but on the other hand the previous solution will not work because c5 is now vacant. Here it looks feasible to mate the black king on on c5, but the obvious plan of Black playing ...Rc3, ...Kc5 and ...Nb6, with White's moves being dxc3 Rd4 and cxb4, fails because the composer has added a pawn on a5 specifically to prevent it. There is usually a connection between the two solutions in a helpmate, so we might guess that the mating position might be related to that in the first part. Composers like to have mating positions which are similar but different, for example one is a reflection of the other or one is obtained from the other by shifting by a rank or file. If we stick to the idea of using the rook along the d-file, how about playing d4, with Black playing ...Rxd4 and White recapturing to mate by Rxd4? This wasn't possible before because c6 was empty (and the queen on c5 covered d4). For this to work e5 and c5 need to be covered. The former is easy, as Black can play ...Ne5, but this leaves only one Black move to block c5, and using the bishop would again cover d4. Once again, an idea which almost works is the stepping-stone to the correct solution. White is playing d4 and Rxd4, so he has a spare move; if we replace d4 by dxc3 and cxb4, then c5 is covered. As in the first solution, it isn't necessary for Black's ...Rd4 to be a capture. This leads at once to the solution} 1... Rc3 2. dxc3+ Rd4 3. cxb4 Ne5 4. Rxd4# {which is a mirrored and shifted version of the mate from the first part.} *

The moremover round proved my downfall, since I failed to solve a fairly straightforward mate in 8, and this allowed Kacper Piorun to take over the leading position by scoring full marks. Here’s a neat mate in 4 which shouldn’t prove too challenging.

[Event "1st Pr, VS SSSR 70"] [Site "?"] [Date "1988.08.22"] [Round "?"] [White "Vladimirov, J."] [Black "Mate in four"] [Result "*"] [Annotator "Nunn,John"] [SetUp "1"] [FEN "K4N1k/3p1p1B/2pB1P2/8/1pp5/4pp2/b4n1R/4b3 w - - 0 1"] [PlyCount "7"] [EventDate "1988.??.??"] {A mate in four moves sounds like a real challenge, but longer problems are often easier to solve than mates in three. One method is to try and mate in three, discover why it doesn't work, and then see how to induce Black to weaken his position in such a way as to invalidate his defence. That technique works quite well in this position. Although the black king is stuck in the corner and pretty much surrounded by white pieces, it's not at all simple to mate. So what potential mating ideas are there?} 1. Rh4 {is the remaining possibility, but this looks more natural in any case as 1...Ng4 is no longer possible.} ({One possibility is to continue} 1. Bg6+ Kg8 2. Rh7 fxg6 (2... c3 $1 {covering the mate on f7}) 3. f7# {but alas Black has}) ({Another idea is} 1. Ng6+ fxg6 2. Bf8 {followed by Bg7#, which can only be met by 2...} Nh3 $1 { Moreover, Black has a threat of 1...Ng4 followed by ...Nxf6, which would break up the mating net, so White must act quickly. Just as in over-the-board play, it's sometimes a good idea to look for a piece which is poorly placed and try to improve its position. There's no obvious way to improve the position of the d6-bishop and knight, while the first move is unlikely to be a check, which rules out the other bishop. That leaves the rook, which is not on the best available square on the h-file, since it cannot move to the g-file for a mate on g8, and it can be cut off by ...Nh3. All this suggests a move up the h-file beyond the h3-square. This would create a threat of 2 Ng6+ fxg6 3 Bf8 which Black would have to counter. That leaves the question of whether h4, h5 or h6 is best. However, 1 Rh5 is answered by 1...Ng4, when 2 Ng6+ fxg6 3 Bf8 fails to 3...Nxf6, and 1 Rh6 is even worse as then 1...Ng4 also attacks the rook.}) { There are three main defences to the threat:} 1... Bc3 {blocks the possible defence ...c3 mentioned above, and so allows} (1... Bb1 {allows the bishop to take on g6, but this moves leaves c4 undefended, which White can exploit by} 2. Bd3+ Kg8 3. Ng6 {threatening mate on h8} fxg6 4. Bxc4#) (1... Ne4 2. Rg4 Nxf6 ( 2... Ng5 3. Rxg5 {only delays the mate on g8 by one move}) {covers g8, but after} 3. Be5 {White gets to mate there in any case}) 2. Bg6+ Kg8 3. Rh7 fxg6 { forced, as ... c3 is impossible} 4. f7# *

Here's the final selfmate in two, not too hard but with a few traps to be avoided. In a selfmate, White is trying to commit suicide by forcing Black to mate him. Black is doing his best to avoid mating White. White plays first, and must force Black to give mate on his second move.

[Event "Suomen Shakki"] [Site "?"] [Date "1996.08.22"] [Round "?"] [White "Kopaev, V."] [Black "Selfmate in two"] [Result "*"] [Annotator "Nunn,John"] [SetUp "1"] [FEN "8/6P1/B3q3/5P1p/2R1p3/3R3Q/3pkPpP/3rn1Kb w - - 0 1"] [PlyCount "4"] [EventDate "1996.??.??"] {The only way to give selfmate is to force the knight to move, and in order to achieve this White needs to check either along the h5-e2 diagonal, forcing ... Nf3#, or along the a6-e2 diagonal, forcing ...Nd3#. At any rate, if the bishop on a6 is to play a part at all, one of the white rooks must make the first move. Almost any move of the d3-rook threatens 2 Qxh5+, while 1 Rd5 actually has two threats: 2 Qxh5+ and 2 Rc6+. The problem with a random rook move, such as 1 Rb3 is that the only threat is 2 Qxh5+ and Black is able to meet this by 1...Qf7!, which both covers h5 and remains on the c4-g8 diagonal to interpose on c4 if the other rook moves away. So how about 1 Rd5 with its twin threats? Unfortunately, that fails to the simple 1...Qxd5 and 2 Qxh5+ can be met by 2... Kd3. So let's switch to the other rook. Once again a random move will threaten 2 Qxh5+, while 1 Rc6 threatens both 2 Qxh5+ and 2 Rd5+. A random move fails to another simple reply: 1...Qxa6, giving the black king a flight square at d3. That leaves three realistic possibilities: 1 Rc6, which simply prevents ... Qxa6, 1 Rcd4 and 1 Rcc3, the last two providing a second guard of d3 so that 1. ..Qxa6 can still be met by 2 Qxh5+. Of these 1 Rcd4 fails to several moves (such as 1...Qf7) since the d4-rook blocks the other rook from moving along the d-file. 1 Rc6 is more tempting, and is only refuted by 1...Qc4!, a defence again based on the idea of removing a guard of d3. That leaves} 1. Rcc3 { , which guards d3 without blocking the d-file for the other rook. This works, the threat being 2 Qxh5+ and the lines being} h4 (1... Qf7 2. Rd5+ {to cut the queen off from c4} Nd3#) (1... Qxf5 2. Rd5+ Nd3#) (1... Qe8 2. Rd7+ Nd3#) (1... Qh6 {1...Qg6 is the same} 2. Rd6+ Nd3#) 2. Qg4+ Nf3# {The white rook moves to d5, d6 and d7, in each case to cut the black queen off from the a6-e2 diagonal. } *

So Kacper Piorun retained his world championship title, which he has now won four years in a row. Second place went to Lithuanian Martynas Limontas, while Marko Filipovic from Croatia finished third (Limontas, Piorun, Filipovic above). I ended up in fourth place, just half a point behind Filipovic.

In response to readers’ comments regarding dress standards in the problem world, here’s proof that not all is lost — photo of Martin Minski, German study composer | Photo: Franziska Iseli

You can also download a PGN of the selected problems without solutions but with pointers by John Nunn to help you solve them, e.g. with ChessBase or a Fritz-compatible program.

John Nunn is a director of Gambit Publications, a leading chess book publisher. They have some interesting new books out this year.

In his day, Lajos Portisch was known for his meticulous opening preparation and in this book he opens his files and shows how key ideas in the Ruy Lopez have evolved from the 1960s to the current era. See GambitBooks.com for more information.

Yochanan Afek, a Grandmaster of Composition and an over-the-board International Master, explores the world of extreme chess tactics, using a host of entertaining examples from over-the-board play and the world of endgame studies. See this page for more information.

These two Gambit books are available in print, Kindle and app form. Using the app, which is available for iOS and Android devices, you can play over all the moves on-screen.

John NunnDr John Nunn (born 1955) is an English grandmaster, author and problem-solver. He was among the world’s leading grandmasters for nearly twenty years, winning four gold medals in chess Olympiads, and is a much-acclaimed writer whose works have won ‘Book of the Year’ awards in several countries. In 2004, 2007 and 2010, Nunn was crowned World Chess Solving Champion. Now 62, he continues to compete successfully in over-the-board and problem-solving events.

See also

3/22/2018 – Chesthetica, an automatic chess problem composer, has been capable of composing all sorts of puzzles using the Digital Synaptic Neural Substrate (DSNS) computational creativity approach for some years now. I feel compelled to remind readers that this new approach has nothing to do with machine learning or artificial neural networks. Creativity is typically not something that can be ‘taught’ or ‘learned’. It also has nothing at all to do with ‘deep learning’. | Graphics: Sample additional Deviant Art images used in the DSNS composing approach

See also

12/17/2017 – Last week we gave you some interesting problems to solve, today we bring you the solutions thereof. And some logical puzzles, which the veteran Super-GM gave us during spectacular walks along the cliffs of Cornwall. For some we need mathematical assistance and invite our readers to provide this. Finally a selection of prize-winning compositions, published over the years, by John Nunn himself. If you do participate there is a a very nice personal prize to win. | Photo: Frederic Friedel

Video

Former World Champion Mikhail Botvinnik liked to play the French and once described it as a 'difficult and dangerous opening'. But in this 60 minutes video IM Andrew Martin suggests an aggressive and little-used idea of the renowned attacking player GM Viktor Kupreichik to counter the French: 1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Nc6 5.Be3!?. Andrew Martin uses the games of Kupreichik to show why this line could catch many French aficionados unprepared and is very dangerous for Black. Attacking players will love this line and the unusual complications that it promotes.